是的，not equal 在 mysql 中存在于 运算符的形式中。语法如下 -
select * from yourtablename where yourcolumnname <> yourvalue;
为了理解上述语法，让我们创建一个表。创建表的查询如下 -
mysql> create table doesnotequaldemo -> ( -> id int not null auto_increment, -> name varchar(20), -> primary key(id) -> );query ok, 0 rows affected (0.98 sec)
使用插入命令在表中插入一些记录。插入记录的查询如下 -
mysql> insert into doesnotequaldemo(name) values(null);query ok, 1 row affected (0.24 sec)mysql> insert into doesnotequaldemo(name) values('john');query ok, 1 row affected (0.18 sec)mysql> insert into doesnotequaldemo(name) values('carol');query ok, 1 row affected (0.43 sec)mysql> insert into doesnotequaldemo(name) values('bob');query ok, 1 row affected (0.13 sec)mysql> insert into doesnotequaldemo(name) values('');query ok, 1 row affected (0.13 sec)mysql> insert into doesnotequaldemo(name) values('larry');query ok, 1 row affected (0.13 sec)mysql> insert into doesnotequaldemo(name) values(null);query ok, 1 row affected (0.10 sec)
使用 select 语句显示表中的所有记录。查询如下 -
mysql> select *from doesnotequaldemo;
以下是输出 -
+----+-------+| id | name |+----+-------+| 1 | null || 2 | john || 3 | carol || 4 | bob || 5 | || 6 | larry || 7 | null |+----+-------+7 rows in set (0.00 sec)
这里是选择所有不等于 null 以及空字符串的记录的查询 -
mysql> select *from doesnotequaldemo where name <> 'null' and name <> '';
以下是输出 -
+----+-------+| id | name |+----+-------+| 2 | john || 3 | carol || 4 | bob || 6 | larry |+----+-------+4 rows in set (0.00 sec)
以上就是mysql 中不存在 not equal 吗？的详细内容。